Yasuteru Yamada, 72, a former antinuclear activist, will lead a group of retirees to the Fukushima No. 1 plant in early July to help clean up the site of Japan’s worst atomic disaster since World War II.

Yamada, a retired Sumitomo Metal Industries Ltd. plant engineer, is waiting for Tokyo Electric Power Co. to allow his volunteer Skilled Veterans Corps to carry out on-site preliminary inspections, a move the government welcomes.

Almost four months since the crisis started, 3,514 workers involved in the cleanup have been exposed to radiation, including nine whose readings breached the annual limit of 250 millisieverts for a nuclear plant worker. Tepco said it had 1,044 workers at the plant as of June 19, about half the number a month earlier.

“I’m not on a suicide mission,” said Yamada, a 1962 University of Tokyo graduate. “I am going to try my best to protect myself and come back alive.”

Tepco is struggling to hire workers at the crippled plant, which has spewed radiation across at least 600 sq. km. The utility, which has about 3,100 employees in its nuclear division, is considering ways to make the best use of its workers, said Ai Tanaka, a company spokeswoman, without elaborating.

“People who are willing to sacrifice their daily lives to help the nation resolve these problems are invaluable,” Goshi Hosono, special advisor to Prime Minister Naoto Kan, said in a news briefing in Tokyo last week. “First we’ll have to check on their health status, as people at an advanced age working in that kind of environment could fall ill.”

Yamada will be part of a five-member team comprised of former Toshiba Corp. and Chiyoda Corp. engineers who will survey damage inside the nuclear plant, he said. More than 200 volunteers, including former nuclear workers, have signed up for the Skilled Veteran Corps, according to its website.

Banri Kaieda, the minister of economy, trade and industry, verbally supported the proposal after he met with Yamada in early June, according to the former engineer.

The retirees will work for free alongside existing Tepco workers in cleanup operations, Yamada said. The government may help subsidize accommodations, meals and transportation costs, he added.

Yamada was about 6 years old and living in Seoul when the atomic bombs devastated Hiroshima and Nagasaki, he said. During his time at Todai, he got involved with leftwing activists who demonstrated against nuclear weapons.

Members of the group reunited at its 50th anniversary last year, and Yamada said he used some of those renewed contacts to telephone and email more than 2,000 of his friends and acquaintances to join his organization.

Tepco is in the process of decontaminating about 105 million liters of radioactive water accumulated in the basements of the Fukushima plant. The company had doused reactors with tens of millions of liters of water to prevent fuel rods from overheating after the March 11 quake and tsunami knocked out power and backup generators.

The efforts have been marred by setbacks. In the past week, Tepco halted tests on a water decontamination system twice after problems with a pump. The stoppages won’t delay plans to achieve stable cooling of the three damaged reactors by mid-July, Junichi Matsumoto, a Tepco general manager, said June 21.

“The shortage of nuclear plant workers will be more severe if it takes more time to decontaminate and decommission the Fukushima No. 1 reactors,” said Tetsuo Ito, head of the Atomic Energy Research Institute at Kinki University. “Using the senior engineers may be a good idea, but the working environment must be really tough.”

On at least two occasions, radiation levels at the plant reached 1 sievert an hour. Thirty minutes of exposure to that dose would trigger nausea. Contamination for four hours might lead to death within four months, according to the U.S. Environmental Protection Agency. Prolonged exposure to radiation in the air, ground and food can cause leukemia and other cancers, according to the London-based World Nuclear Association.

One Tepco worker in his 30s may have been exposed to 678.1 millisieverts after he was involved in a reactor operation on March 11, spokesman Naoki Tsunoda said.

Yamada and his fellow pensioners said they’re aware of the risks of entering the nuclear station.

“I am mentally prepared for death, but I’m not a kamikaze,” Yamada said. “The kamikaze were making irrational, obligatory self-sacrifices. What I’m doing is self-motivated and rational.”